The British model Jourdan Dunn has added her voice to a campaign led by black models for more diversity in the fashion industry. Speaking in an exclusive interview in the Fashion, the new biannual fashion magazine from the Guardian and Observer, Dunn says: "The people who control the industry … say if you have a black face on a magazine cover it won't sell, but there's no real evidence for that. It's lazy."

"I want to talk about what goes on. A lot of people are scared to speak up. People think it's all glamorous and good and that all models get treated the same, but there is still a lot of BS that happens," Dunn has told the Fashion.

The British Fashion Council responded by saying that although it cannot control model casting, it "strongly assert[s] that all participating designers should recognise that London is one of the most multi-cultural cities in the world and should consider reflecting this demographic at their shows and presentations."

However Didier Grumbach, president of the French equivalent of the BFC, described the criticism as "unreasonable".

Naomi Campbell is backing the campaign for diversity, as is the black singer and model VV Brown, who wrote in the Guardian this week that "the next time I sit at a fashion show, I hope to see a true representation of race and culture, beyond tokenism. I want my children to receive messages that tell them they are beautiful."

Dunn is hopeful that social media will amplify the voices of black models and serve as a catalyst for progress. "With social media everything has changed," she says, noting that some fashion houses now take into account the number of Twitter followers a model has when deciding which model will best bring attention to their catwalk or advertising campaign. "It's great, especially for models who want to be listened to," she says in the interview.